1. Field of the Invention
The present invention relates to a multidirectional operating switch mainly used for operating electronic equipment mounted on a car.
2. Background Art
In recent years, a car having a switch disposed on a steering wheel has become familiar to people. While holding the steering wheel, the driver operates the switch with the finger to control electronic equipment such as a car audio device or an automotive air conditioner. Under the circumstances, there has been a growing demand for a switch with user-friendly and reliable operation. Hereinafter, a conventional multidirectional operating switch will be described with reference to FIGS. 12 through 14B.
FIG. 12 is a sectional view of a conventional multidirectional operating switch. FIG. 13 is an exploded perspective view of the switch. FIGS. 14A and 14B are sectional views of the multidirectional operating switch of FIG. 12 in operation. Multidirectional operating switch 20 has case 1, operating body 2, operation button 3, push piece 4, holding base 5, wiring board 6, and push elements 10A and 10B.
Case 1 is made of insulating resin and is formed into a box-like shape. Case 1 has opening 1A on the top. Operating body 2 is made of insulating resin and is formed into a cylindrical shape. Operating body 2 has operation face 2F on the top. Operation face 2F is exposed out of opening 1A. Operating body 2 is accommodated in case 1. Operating body 2 has a plurality of operating sections 2A where translucent display sections 2B are exposed at predetermined positions in the periphery of operation face 2F.
Operation button 3 has a cylindrical shape. On the lower end of push piece 4, push section 4A protrudes downwardly. Push piece 4 is disposed inside operation button 3. Operation button 3 is accommodated in recess 2G disposed in the center of operating body 2 so as to be movable in the vertical direction but so as not to be upwardly pulled off.
Holding base 5 is made of insulating resin and is formed into a bottom-opened box shape. In the periphery of the center of the upper surface of holding base 5, locking sections 5A, each of which is formed into an upwardly protruding hook, are oppositely disposed. Locking sections 5A are held by holding base 5 so as to be engaged with catching holes 2C formed under recess 2G of operating body 2. This allows operating body 2 to be movable in “crisscross” (i.e. front, back, right, and left) directions.
Wiring board 6 has a plurality of wiring patterns (not shown) on both surfaces. On the upper surface of wiring board 6, central switch 7 formed of, for example, a push switch having push button 7A thereon, is mounted. In the periphery of central switch 7, a plurality of peripheral switches 8 formed of a push switch, light-emitting diodes (LEDs) 9, and other electronic components are mounted on the upper surface of wiring board 6. Peripheral switches 8 are arranged at four equally-spaced positions (of front, back, right, and left) so as to be concentric with central switch 7.
Each of push elements 10A and 10B has a cylindrical upper part and a disc-like lower part. Push element 10A is inserted through guiding hole 5B formed in the center of holding base 5. The lower end of push element 10A makes contact with the top surface of push button 7A of central switch 7. The upper end of push element 10A makes contact with push section 4A disposed at the lower end of push piece 4.
Push elements 10B are inserted through guiding holes 5C, respectively. The lower end of each push element 10B makes contact with the top surface of push button 8A of peripheral switches 8, and the upper end of each push element 10B makes contact with downwardly protruding push section 2D disposed in the vicinity of the periphery of operating body 2.
Case 1 accommodating operating body 2 and holding base 5 is fixed to wiring board 6 with screws 11. Multidirectional operating switch 20 is thus completed.
Multidirectional operating switch 20 is attached between the steering wheel and an airbag built-in pad, such that operation face 2F of operating body 2 and the top surface of push button 3 face the driver. Central switch 7 and peripheral switches 8 are electrically connected to the electronic circuits of the car (not shown) via connectors and lead wires (not shown).
FIG. 14 shows the state where the driver pushes right-side operating section 2A with the thumb while holding the steering wheel. At that moment, operating body 2 has a right-downward tilt around engaging section 2E as a fulcrum at which locking section 5A engages in catching hole 2C disposed in the lower left. The tilt allows push section 2D disposed at the lower end of operating section 2A to move downward and press push button 8A via push element 10B, so that corresponding peripheral switch 8 is operated. In response to signals from peripheral switch 8, a predetermined operation is carried out via a corresponding electronic circuit such as, for example, the audio device being set into a selection mode for selecting compact disc-music numbers.
Next, the driver pushes operation button 3 in the center, as shown in FIG. 14B. The pushing force on operation button 3 lowers push piece 4, allowing push section 4A to press push button 7A via push element 10A, so that central switch 7 is operated. In response to signals from central switch 7, a predetermined operation is carried out. For example, the music number that has been selected in the operation by operating section 2A is played.
When the driver pushes operating section 2A on the upper side or the lower side of operating body 2, operating body 2 tilts in the pushed direction, and peripheral switch 8 disposed under the pushed position is operated. Through the operation, for example, the volume level of the audio device is controlled.
In the night or in a dark place, such as in a tunnel, when the driver operates a lighting switch (not shown) other than multidirectional operation switch 20, an electronic circuit of the car allows LEDs 9 to emit light. The light of each LED 9 goes through a cylindrical light guiding section of holding base 5 and illuminates display section 2B of operating section 2A disposed above. Such illuminated operating section 2A provides the driver with easy recognition for operation.
As is shown in FIG. 14A, in response to the driver's pushing force on right-side operating section 2A, operating body 2 has a right-downward tilt around engaging section 2E as a fulcrum on off-centered in the left under operating body 2. At that time, push section 4A at the lower end of operation button 3 slightly lowers with the tilt of operating body 2, by which push button 7A can be lowered. If the components have poor accuracy in dimension or have expansion or contraction in an operating environment, unintended pushing force can be exerted on central switch 7.
As described above, the tilt of operating body 2 in response to the pushing operation on peripheral operating section 2A can invite unwanted electrical connection of central switch 7 disposed under operation button 3, resulting in unintended operation of electronic equipment, such as an audio device.